Methods of forming capacitors DRAM arrays, and monolithic integrated circuits

ABSTRACT

The invention includes a number of methods and structures pertaining to semiconductor circuit technology, including: methods of forming DRAM memory cell constructions; methods of forming capacitor constructions; DRAM memory cell constructions; capacitor constructions; and monolithic integrated circuitry. The invention includes a method of forming a capacitor comprising the following steps: a) forming a mass of silicon material over a node location, the mass comprising exposed doped silicon and exposed undoped silicon; b) substantially selectively forming rugged polysilicon from the exposed undoped silicon and not from the exposed doped silicon; and c) forming a capacitor dielectric layer and a complementary capacitor plate proximate the rugged polysilicon and doped silicon. The invention also includes a capacitor comprising: a) a first capacitor plate; b) a second capacitor plate; c) a capacitor dielectric layer intermediate the first and second capacitor plates; and d) at least one of the first and second capacitor plates comprising a surface against the capacitor dielectric layer and wherein said surface comprises both doped rugged polysilicon and doped non-rugged polysilicon.

TECHNICAL FIELD

The invention pertains to semiconductor capacitor constructions and tomethods of forming semiconductor capacitor constructions. The inventionis thought to have particular significance in application to methods offorming dynamic random access memory (DRAM) cell structures, to DRAMcell structures, and to integrated circuitry incorporating DRAM cellstructures.

BACKGROUND OF THE INVENTION

A commonly used semiconductor memory device is a DRAM cell. A DRAM cellgenerally consists of a capacitor coupled through a transistor to abitline. A semiconductor wafer fragment 10 is illustrated in FIG. 1showing a prior art DRAM array 83. Wafer fragment 10 comprises asemiconductive material 12, field oxide regions 14, and wordlines 24 and26. Wordlines 24 and 26 comprise a gate oxide layer 16, a polysiliconlayer 18, a silicide layer 20 and a silicon oxide layer 22. Silicidelayer 20 comprises a refractory metal silicide, such as tungstensilicide, and polysilicon layer 18 typically comprises polysilicon dopedwith a conductivity enhancing dopant. Nitride spacers 30 are laterallyadjacent wordlines 24 and 26.

Electrical node locations 25, 27 and 29 are between wordlines 24 and 26and are electrically connected by transistor gates comprised bywordlines 24 and 26. Node locations 25, 27 and 29 are diffusion regionsformed within semiconductive material 12.

A borophosphosilicate glass (BPSG) layer 34 is over semiconductivematerial 12 and wordlines 24 and 26. An oxide layer 32 is providedbetween BPSG layer 34 and material 12. Oxide layer 32 inhibits diffusionof phosphorus from BPSG layer 34 into underlying materials.

Conductive pedestals 54, 55 and 56 extend through BPSG layer 34 to nodelocations 25, 27 and 29, respectively. Capacitor constructions 62 and 64contact upper surfaces of pedestals 54 and 56, respectively. Capacitorconstructions 62 and 64 comprise a storage node layer 66, a dielectriclayer 68, and a cell plate layer 70. Dielectric layer 68 comprises anelectrically insulative layer, such as silicon nitride. Cell plate layer70 comprises conductively doped polysilicon, and may alternatively bereferred to as a cell layer 70. Storage node layer 66 comprisesconductively doped hemispherical grain (HSG) polysilicon.

A conductive bitline plug 75 contacts an upper surface of pedestal 55.Bitline plug 75 may comprise, for example, tungsten. Together, bitlineplug 75 and pedestal 55 comprise a bitline contact 77.

A bitline 76 extends over capacitors 62 and 64 and in electricalconnection with bitline contact 77. Bitline 76 may comprise, forexample, aluminum.

The capacitors 62 and 64 are electrically connected to bitline contact77 through transistor gates comprised by wordlines 26. A first DRAM cell79 comprises capacitor 62 electrically connected to bitline 76 through awordline 26 and bitline contact 77. A second DRAM cell 81 comprisescapacitor 64 electrically connected to bitline 76 through wordline 26and bitline contact 77. DRAM array 83 comprises first and second DRAMcells 79 and 81.

If capacitors 62 and 64 are inadvertently shorted together, a so-called“double bit failure” will occur. Such double bit failures can occur if astray piece of polysilicon, or HSG polysilicon, breaks off duringformation of DRAM array 83 and disadvantageously electrically connectscapacitors 62 and 64. Prior art capacitor fabrication methods employchemical-mechanical polishing (CMP) of HSG polysilicon. HSG polysiliconpieces can break off during such CMP processes and cause double bitfailures. It would be desirable to develop alternative DRAMconstructions which could be formed by methods avoiding double bitfailures.

SUMMARY OF THE INVENTION

The invention includes a number of methods and structures pertaining tosemiconductor circuit technology, including: methods of forming DRAMmemory cell constructions; methods of forming capacitor constructions;DRAM memory cell constructions; capacitor constructions; and integratedcircuitry. For instance, the invention encompasses a method of forming acapacitor wherein a mass of silicon material is formed over a nodelocation, and wherein the mass comprises exposed doped silicon andexposed undoped silicon. The method can further include substantiallyselectively forming rugged polysilicon from the exposed undoped siliconand not from the exposed doped silicon. Also, the method can includeforming a capacitor dielectric layer and a complementary capacitor plateproximate the rugged polysilicon and doped silicon.

As another example, the invention encompasses a capacitor having acapacitor dielectric layer intermediate a first capacitor plate and asecond capacitor plate, wherein at least one of the first and secondcapacitor plates has a surface against the capacitor dielectric layer,and wherein said surface comprises both doped rugged polysilicon anddoped non-rugged polysilicon.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the invention are described below withreference to the following accompanying drawings.

FIG. 1 is a schematic cross-sectional view of a semiconductor waferfragment comprising a prior art DRAM array.

FIG. 2 is a schematic cross-sectional process view of a semiconductorwafer fragment at preliminary processing step of a processing method ofthe present invention.

FIG. 3 is a view of the FIG. 2 wafer fragment at a processing stepsubsequent to that of FIG. 2.

FIG. 4 is a view of the FIG. 2 wafer fragment at a processing stepsubsequent to that of FIG. 3.

FIG. 5 is a view of the FIG. 2 wafer fragment at a processing stepsubsequent to that of FIG. 4.

FIG. 6 is a view of the FIG. 2 wafer fragment at a processing stepsubsequent to that of FIG. 5.

FIG. 7 is a view of the FIG. 2 wafer fragment at a processing stepsubsequent to that of FIG. 6.

FIG. 8 is a view of the FIG. 2 wafer fragment at a processing stepsubsequent to that of FIG. 7.

FIG. 9 is a top view of the FIG. 8 wafer fragment.

FIG. 10 is a view of the FIG. 2 wafer fragment at a processing stepsubsequent to that of FIG. 8.

FIG. 11 is a view of the FIG. 2 wafer fragment at a processing stepsubsequent to that of FIG. 10.

FIG. 12 is a view of the FIG. 2 wafer fragment at a processing stepsubsequent to that of FIG. 11.

FIG. 13 is a view of the FIG. 2 wafer fragment at a processing stepsubsequent to that of FIG. 12.

FIG. 14 is a view of the FIG. 2 wafer fragment at a processing stepsubsequent to that of FIG. 6 processed according to a second embodimentof the present invention.

FIG. 15 is a view of the FIG. 2 wafer fragment at a step subsequent tothat of FIG. 14.

FIG. 16 is a top view of the FIG. 15 wafer fragment.

FIG. 17 is a view of the FIG. 2 wafer fragment at a step subsequent tothat of FIG. 15.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

This disclosure of the invention is submitted in furtherance of theconstitutional purposes of the U.S. Patent Laws “to promote the progressof science and useful arts” (Article 1, Section 8).

Methods of forming DRAM arrays of the present invention are describedwith reference to FIGS. 2-17, with FIGS. 2-13 pertaining to a firstembodiment of the invention, and FIGS. 14-17 pertaining to a secondembodiment of the invention. In describing the first embodiment of thepresent invention, like numerals from the preceding discussion of theprior art are utilized where appropriate, with differences beingindicated by the suffix “a” or with different numerals.

Referring to FIG. 2, a semiconductor wafer fragment 10 a is illustratedat a preliminary step of a process of the present invention. Waferfragment 10 a comprises a semiconductive material 12 a, field oxideregions 14 a, and a thin gate oxide layer 16 a. Over gate oxide layer 16a is formed polysilicon layer 18 a, silicide layer 20 a and siliconoxide layer 22 a. Silicide layer 20 a comprises a refractory metalsilicide, such as tungsten silicide, and polysilicon layer 18 atypically comprises polysilicon doped with a conductivity enhancingdopant. Layers 16 a, 18 a, 20 a and 22 a can be formed by conventionalmethods.

Referring next to FIG. 3, polysilicon layer 18 a, silicide layer 20 aand silicon oxide layer 22 a are etched to form wordlines 24 a and 26 a.Such etching can be accomplished by conventional methods. Betweenwordlines 24 a and 26 a are defined electrical node locations 25 a, 27 aand 29 a, with wordlines 26 a comprising transistor gates whichelectrically connect node locations 25 a, 27 a, and 29 a. Node locations25 a, 27 a and 29 a are diffusion regions formed within semiconductivematerial 12 a.

Referring to FIGS. 4 and 5, a nitride layer 28 a is provided overwordlines 24 a and 26 a and subsequently etched to form nitride spacers30 a laterally adjacent wordlines 24 a and 26 a.

Referring to FIG. 6, an insulative material layer 34 a is formed overmaterial 12 a and over wordlines 24 a and 26 a. Insulative layer 34 amay comprise, for example, BPSG, and can be formed by conventionalmethods. Insulative layer 34 a comprises an upper surface 35 a. Openings38 a, 39 a and 40 a are formed extending through insulative layer 34 ato node locations 25 a, 27 a and 29 a, respectively.

Referring to FIG. 7, an undoped silicon layer 100 is formed overinsulative layer 34 a and within openings 38 a, 39 a and 40 a. Undopedsilicon layer 100 narrows openings 38 a, 39 a and 40 a, but does notfill such openings. Undoped silicon layer 100 preferably has a thicknessof from about 50 Angstroms to about 1000 Angstroms, with a thickness ofabout 300 Angstroms being most preferred. Undoped silicon layer 100preferably comprises substantially amorphous silicon. Such substantiallyamorphous layer can be 5-10% crystalline. Undoped silicon layer 100 canbe formed by conventional methods, such as, for example, by depositionutilizing either silane or disilane. For purposes of the continuingdiscussion, and for interpreting the claims that follow, “undoped”silicon is defined as silicon having a dopant concentration of less than5×10¹⁸ atoms/cm³, and “doped” silicon is defined as silicon having adopant concentration of at least 5×10¹⁸ atoms/cm³. “Undoped” siliconpreferably comprises less than or equal to 1×10¹⁸ atoms/cm³, and “doped”silicon preferably comprises at least 1×10¹⁹ atoms/cm³.

A doped silicon layer 102 is formed over undoped silicon layer 100 andwithin openings 38 a, 39 a and 40 a. In the shown embodiment of theinvention, doped layer 102 completely fills openings 38 a, 39 a and 40a. However, in alternative embodiments of the invention, such as theembodiment discussed below with reference to FIGS. 14-17, layer 102 canonly partially fill openings 38 a, 39 a and 40 a. As will be appreciatedby persons of ordinary skill in the art, the thickness of layer 102 willvary depending on whether layer 102 is chosen to completely fillopenings 38 a, 39 a and 40 a, or to partially fill such openings. Dopedsilicon layer 102 preferably comprises doped polysilicon, and can beformed by conventional methods.

After formation of layers 100 and 102, an upper surface of waferfragment 10 a is planarized to remove layers 100 and 102 from overinsulative layer 34 a. Such planarization can be accomplished by, forexample, chemical-mechanical polishing (CMP).

Referring to FIG. 8, after the above-discussed planarization, pedestals104, 106 and 108 remain in openings 38 a, 39 a and 40 a (shown in FIG.7), respectively. Pedestals 104, 106 and 108 comprise undoped siliconlayer 100 and doped silicon layer 102, and are over node locations 25 a,27 a and 29 a, respectively. Pedestals 104, 106 and 108 also compriseexposed upper surfaces 116, 118 and 120, respectively.

FIG. 9 illustrates a top view of the FIG. 8 wafer fragment, and showsthat pedestals 104, 106 and 108 actually comprise a core of dopedsilicon layer 102 surrounded by undoped silicon layer 100.

Referring again to FIG. 8, insulative layer 34 a is selectively removedrelative to the silicon of pedestals 104, 106 and 108 to form a newupper surface 37 a lower than previous upper surface 35 a (shown in FIG.7). The preferred BPSG insulative layer 34 a can be selectively removedrelative to pedestals 104, 106 and 108 using a conventional oxide etch.The selective removal of insulative layer 34 a exposes a sidewallsurface 110 of pedestal 104, a sidewall surface 112 of pedestal 106, anda sidewall surface 114 of pedestal 108. Sidewall surfaces 110, 112 and114 comprise undoped silicon layer 100. Additionally, in the shownembodiment a portion of undoped silicon layer 100 is below upper surface37 a of BPSG layer 34 a, and remains unexposed. The depth of removal ofinsulative layer 34 a can be controlled by a number of methods. Forexample, layer 34 a could be removed via a timed etch. As anotherexample, an etch stop layer could be formed within layer 34 a at adesired depth of surface 37 a. An example of a layer 34 a comprising anetch stop layer is a layer comprising BPSG and having a silicon nitrideetch stop layer formed within the BPSG at a level of upper surface 37 a.

As exposed sidewall surfaces 110, 112 and 114 of pedestals 104, 106 and108 comprise undoped silicon layer 100, and as exposed upper surfaces116, 118 and 120 of the pedestals comprise exposed doped silicon layer102, as well as exposed undoped silicon layer 100, the pedestalscomprise exposed doped silicon and exposed undoped silicon at theprocessing step of FIG. 8.

Referring to FIG. 10, a rugged polysilicon layer 122 is substantiallyselectively formed from the exposed undoped silicon of surfaces 110, 112114, 116, 118, and 120 (shown in FIG. 8), and not from the exposed dopedsilicon of surfaces 116, 118 and 120. Rugged polysilicon layer 122comprises materials selected from the group consisting of HSG andcylindrical grain polysilicon. The substantially selective formation ofa preferred HSG polysilicon layer 122 from undoped silicon surfaces butnot from doped silicon surfaces can be accomplished by the followingprocess.

First, wafer fragment 10 a is loaded into a conventional chemical vapordeposition (CVD) furnace and is subjected to an in situ hydrofluoricacid (HF) clean to remove native oxide. The in situ HF clean preferablycomprises a flow rate of 85 standard cubic centimeters per minute (sccm)of HF gas and 8500 sccm of H₂O gas, at a pressure of 15 Torr, for a timeof about 20 seconds. Wafer fragment 10 a is then exposed to silane toform amorphous silicon seeds on the undoped silicon. Wafer fragment 10 ais then annealed for approximately 20 minutes at about 560° C. Theseeding and anneal steps convert undoped amorphous silicon into ruggedpolysilicon (such as hemispherical grain polysilicon), while leavingexposed doped silicon layers not converted to rugged polysilicon. It isnoted that the above-described process for forming HSG polysilicon doesnot require disilane, and hence is different than the “pure” selectivehemispherical grain deposition utilized in high vacuum tools withdisilane.

After the formation of rugged polysilicon layer 122, a short polysiliconetch is performed to remove any monolayers of silicon deposited oninsulative layer 34 a during the above-described seeding step. Suchpolysilicon etch can be accomplished with conventional conditions, andmay comprise either a wet etch or a dry etch.

The above-described process for forming rugged polysilicon layer 122advantageously avoids formation of polysilicon on a back side (notshown) of wafer fragment 10 a. The method can also avoid double bitfailures by removing monolayers of silicon after formation of HSG.

Subsequent thermal processing of pedestals 104, 106 and 108 canout-diffuse dopant from doped polysilicon layer 102 into undoped siliconlayer 100 (shown in FIG. 8), to convert unexposed portions of undopedsilicon layer 100 into a doped polysilicon layer 119. Subsequent thermalprocessing can also out-diffuse dopant from doped polysilicon layer 102into rugged polysilicon layer 122. Thermal processing to out-diffusedopant from doped polysilicon layer 102 into adjacent undoped layerswill typically comprise temperatures of 800° C. or greater.

Referring to FIG. 11, a dielectric layer 124 is provided over insulativelayer 34 a and over pedestals 104, 106 and 108. Dielectric layer 124will typically comprise silicon nitride and/or silicon oxide, althoughother suitable materials are known to persons of skill in the art. Acapacitor cell plate layer 126 is provided over dielectric layer 124.Capacitor cell plate layer 126 will typically comprise dopedpolysilicon, but other suitable materials are known to persons of skillin the art.

Referring to FIG. 12, a patterned masking layer 128 is formed overpedestals 104 and 108, leaving pedestal 106 exposed. Subsequently, waferfragment 10 a is subjected to etching conditions which remove cell platelayer 126 and dielectric layer 124 from proximate pedestal 106. Aftersuch etching, pedestal 106 is electrically isolated from pedestals 104and 108, with the only remaining electrical connection between pedestal106 and pedestals 104 and 108 being through wordlines 26 a. Methods forremoving cell plate layer 126 and dielectric layer 124 from proximatepedestal 106 are known to persons of ordinary skill in the art.

Referring to FIG. 13, masking layer 128 is removed and an insulativelayer 130 is formed over pedestals 104, 106 and 108, and over insulativelayer 34 a. Insulative layer 130 may comprise, for example, BPSG, andcan be formed by conventional methods. A conductive bitline plug 75 a isformed extending through insulative layer 130 and in electrical contactwith pedestal 106. Pedestal 106 comprises rugged lateral surfaces 136and an upper surface 118 which has a predominant portion not comprisingrugged-polysilicon. As shown, the non-rugged polysilicon of uppersurface advantageously provides a smooth landing region for bitline plug75 a.

Pedestal 106 and bitline plug 75 a together form a bitline contact 77 a.A bitline 76 a is formed over bitline plug 75 a and in an electricalconnection with pedestal 106 through bitline plug 75 a. Bitline 76 a andbitline plug 75 a may be formed by conventional methods.

The above-described method can be used to avoid chemical-mechanicalpolishing of a rugged polysilicon layer, thus avoiding a potentialsource of double bit failures.

FIG. 13 illustrates a DRAM array 83 a of the present invention. DRAMarray 83 a comprises capacitors 62 a and 64 a. Capacitors 62 a and 64 acomprise capacitor storage nodes 132 and 134, respectively, whichcomprise doped polysilicon layer 102, doped polysilicon layer 119 andrugged-polysilicon layer 122. As the doped polysilicon layer 119 isformed from the undoped silicon layer 100 (shown in FIG. 8), the undopedsilicon layer 100 and doped silicon layer 102 of pedestals 104 and 108in FIG. 8 together define capacitor storage nodes 132 and 134. Storagenodes 132 and 134 have rugged-polysilicon-comprising lateral surfaces138 and 140, respectively. Storage nodes 132 and 134 further comprisetop surfaces 116 and 120, respectively, which have predominant portionswhich do not comprise rugged-polysilicon.

Cell plate layer 126 and dielectric layer 124 are operatively proximateto storage nodes 132 and 134 so that the storage nodes, together withcell plate layer 126 and dielectric layer 124, form operative capacitors62 a and 64 a. Dielectric layer 124 contacts rugged surfaces 138 and140, as well as top surfaces 116 and 120 of storage nodes 132 and 134.

Capacitors 62 a and 64 a are connected to pedestal 106 through wordlines26 a. Capacitor 62 a, together with bitline contact 77 a and aninterconnecting wordline 26 a, comprises a first DRAM cell 79 a.Capacitor 64 a, together with bitline contact 77 a and aninterconnecting wordline 26 a, comprises a second DRAM cell 81 a.

A second embodiment of the invention is described with reference toFIGS. 14-17. In describing the embodiment of FIGS. 14-17, numberingsimilar to that utilized above for describing the embodiment of FIGS.2-13 is utilized, with differences being indicated by the suffix “b”, orby different numbers.

Referring to FIG. 14, a wafer fragment 10 b is shown at a processingstep subsequent to that of the above-discussed FIG. 6. Wafer fragment 10b comprises wordlines 24 b and 26 b having constructions identical tothat discussed above with regard to the prior art. Wafer fragment 10 bfurther comprises node locations 25 b, 27 b and 29 b between wordlines24 b and 26 b. Wafer fragment 10 b also comprises a semiconductorsubstrate 12 b and field oxide regions 14 b formed over substrate 12 b.

An insulative material layer 34 b is formed over wordlines 24 b and 26b, and over semiconductive material 12 b. Insulative layer 34 b maycomprise a number of materials known to persons of ordinary skill in theart, including BPSG. Openings 38 b, 39 b and 40 b extend throughinsulative layer 34 b to node locations 25 b, 27 b and 29 b,respectively.

A first undoped silicon layer 146 extends over insulative layer 34 b andwithin openings 38 b, 39 b and 40 b. Undoped silicon layer 146preferably comprises amorphous silicon, and preferably has a thicknessof from about 50 Angstroms to about 500 Angstroms. Undoped silicon layer146 can be formed by conventional methods, such as CVD. Undoped siliconlayer 146 narrows openings 38 b, 39 b and 40 b.

A doped silicon layer 148 is formed over undoped silicon layer 146 andwithin narrowed openings 38 b, 39 b and 40 b. Doped silicon layer 148preferably comprises polysilicon, and can be formed by conventionalmethods, such as CVD. Doped silicon layer 148 preferably has a thicknessof from about 50 Angstroms to about 500 Angstroms, and preferably doesnot fill openings 38 b, 39 b and 40 b. Rather, doped silicon layer 148preferably further narrows openings 38 b, 39 b and 40 b beyond whereopenings 38 b, 39 b and 40 b were narrowed by undoped silicon layer 146.

A second undoped silicon layer 150 is formed over doped silicon layer148 and within openings 38 b, 39 b and 40 b. Undoped silicon layer 150preferably comprises the same preferable materials of first undopedsilicon layer 146. Accordingly, second undoped silicon layer 150preferably comprises substantially amorphous silicon. Second undopedsilicon layer 150 preferably has a thickness of from 50 to 500Angstroms, and in the shown preferred embodiment does not fill openings38 b, 39 b and 40 b.

After formation of layers 146, 148 and 150, wafer fragment 10 b isplanarized to remove layers 146, 148 and 150 from over insulative layer34 b. Such planarizing may be accomplished by, for example,chemical-mechanical polishing. After the planarization of wafer fragment10 b, pedestals 104 b, 106 b and 108 b (shown in FIG. 15) having uppersurfaces 116 b, 118 b and 120 b (shown in FIG. 15), respectively, remainwithin openings 38 b, 39 b and 40 b.

Referring to FIG. 15, the material of insulative layer 34 b isselectively removed relative to the silicon of pedestals 104 b, 106 band 108 b to form an upper surface 37 b of insulative layer 34 b whichis below upper surfaces 116 b, 118 b and 120 b of pedestals 104 b, 106 band 108 b. The removal of insulative layer 34 b exposes sidewalls 110 b,112 b and 114 b of pedestals 104 b, 106 b and 108 b, respectively. Theexposed sidewalls 110 b, 112 b and 114 b comprise first undoped siliconlayer 146. Additionally, in the shown embodiment a portion of undopedsilicon layer 146 is below upper surface 37 b of BPSG layer 34 b, andremains unexposed. In the shown preferred embodiment, pedestals 104 b,106 b and 108 b comprise hollow interiors corresponding to openings 38b, 39 b and 40 b (shown in FIG. 14). The depth of removal of insulativelayer 34 b can be controlled by methods such as those discussed abovewith reference to FIG. 8 for controlling the depth of removal ofinsulative layer 34 a.

Referring to FIG. 16, which is a top view of the FIG. 15 wafer fragment,second undoped silicon layer 150 lines the hollow interiorscorresponding to openings 38 b, 39 b and 40 b.

Referring to FIG. 17, wafer fragment 10 b is subjected to processingidentical to that discussed above regarding FIG. 10 to convert exposedundoped silicon surfaces to rugged-polysilicon surfaces, while notroughening exposed doped silicon surfaces. Such treatment forms arugged-polysilicon layer 122 b from exposed portions of first undopedsilicon layer 146 (shown in FIG. 15) and forms a rugged-polysiliconlayer 160 from second undoped silicon layer 150 within the interiors ofpedestals 104 b, 106 b and 108 b. Such processing also out-diffusesdopant from doped silicon layer 148 into adjacent undoped layers andthus converts unexposed portions of undoped layer 146 (shown in FIG. 15)into doped regions 119 b.

Subsequent processing, similar to the processing discussed above withreference to FIGS. 11-13, may be conducted to form a DRAM array frompedestals 104 b, 106 b and 108 b. In such DRAM array, pedestals 104 band 108 b would be storage nodes for first and second capacitors,respectively, and pedestal 106 b would form a conductive contact to abitline. Such subsequent processing is not illustrated as thedescription above regarding FIGS. 11-13 is sufficient to enable a personof skill in the art to form a DRAM array from the structure of FIG. 17.It is noted, however, that the storage nodes formed from pedestals 104 band 108 b would differ from the storage nodes of FIG. 13 in that thestorage nodes formed from pedestals 104 b and 108 b would have the shapeof upwardly open containers, with the interiors of such containers beinglined by rugged-polysilicon layer 160.

The above-described DRAMs and capacitors of the present invention can beimplemented into monolithic integrated circuitry, includingmicroprocessors.

To aid in interpretation of the claims that follow, the term“semiconductive substrate” is defined to mean any constructioncomprising semiconductive material, including, but not limited to, bulksemiconductive materials such as a semiconductive wafer (either alone orin assemblies comprising other materials thereon), and semiconductivematerial layers (either alone or in assemblies comprising othermaterials). The term “substrate” refers to any supporting structure,including, but not limited to, the semiconductive substrates describedabove.

In compliance with the statute, the invention has been described inlanguage more or less specific as to structural and methodical features.It is to be understood, however, that the invention is not limited tothe specific features shown and described, since the means hereindisclosed comprise preferred forms of putting the invention into effect.The invention is, therefore, claimed in any of its forms ormodifications within the proper scope of the appended claimsappropriately interpreted in accordance with the doctrine ofequivalents.

What is claimed is:
 1. A method of forming a capacitor comprising thefollowing steps: forming a solid mass of silicon material within anopening formed over a node location defined by a doped region of thesemiconductor substrate, the mass comprising two forms of silicon incontact with one another, the mass including undoped silicon in physicalcontact with the node location; substantially selectively forming ruggedpolysilicon from one of the forms of silicon and not from another of theforms of silicon; and forming a capacitor dielectric layer and acomplementary capacitor plate proximate the rugged polysilicon.
 2. Themethod of claim 1 wherein the two forms of silicon comprise dopedsilicon and undoped silicon.
 3. The method of claim 2 wherein the dopedsilicon comprises a dopant concentration of at least 5×10¹⁸ atoms/cm³and wherein the undoped silicon comprises a dopant concentration of lessthan 5×10¹⁸ atoms/cm³.
 4. The method of claim 2 wherein the dopedsilicon comprises a dopant concentration of at least 1×10¹⁹ atoms/cm³and wherein the undoped silicon comprises a dopant concentration of lessthan or equal to 1×10¹⁸ atoms/cm³.
 5. A method of forming a capacitorcomprising the following steps: forming a solid mass of silicon materialfilling an opening formed over a node location defined by a doped regionof the semiconductor substrate, the mass comprising exposed dopedsilicon and exposed undoped silicon in contact with one another, andincluding undoped silicon in physical contact with the node location;substantially selectively forming rugged polysilicon from the exposedundoped silicon and not from the exposed doped silicon; and forming acapacitor dielectric layer and a complementary capacitor plate proximatethe rugged polysilicon and doped silicon.
 6. The method of claim 5wherein the step of forming a mass of silicon material comprises forminga layer of doped silicon between two layers of undoped silicon.
 7. Themethod of claim 5 further comprising conductively doping the undopedsilicon after forming the rugged polysilicon.
 8. The method of claim 5further comprising, after forming the rugged polysilicon, out-diffusingimpurity from the doped silicon into the undoped silicon to conductivelydope the undoped silicon.
 9. The method of claim 5 wherein the step offorming the mass comprises forming the exposed undoped silicon to besubstantially amorphous.
 10. The method of claim 5 wherein the step offorming the mass comprises forming the exposed doped silicon to besubstantially polycrystalline.
 11. A method of forming a capacitorcomprising the following steps: forming an insulative layer over a nodelocation defined by a doped region of the semiconductor substrate;forming an opening through the insulative layer to the node location;forming a solid mass comprising two forms of silicon filling the openingand in contact with one another, the two forms of silicon togetherforming a capacitor storage node, the two forms of silicon includingundoped silicon in physical contact with the node location; exposing thetwo forms of silicon to common subsequent processing conditions whichsubstantially selectively form rugged polysilicon from one of theexposed two forms of silicon and not from another of the exposed twoforms of silicon; forming a dielectric layer proximate the storage node;and forming a cell plate layer proximate the dielectric layer.
 12. Themethod of claim 11 wherein the two forms of silicon comprise dopedsilicon and unidoped silicon.
 13. A method of forming a capacitorcomprising the following steps: forming an insulative layer over a nodelocation defined by a doped region of the semiconductor substrate;forming an opening through the insulative layer to the node location;forming a solid mass of silicon material filling the opening, thesilicon material comprising doped silicon and undoped silicon in contactwith one another and defining a capacitor storage node, a portion of theundoped silicon being in physical contact with the node location;removing a portion of the insulative layer to expose a sidewall surfaceof the storage node, the exposed sidewall surface comprising undopedsilicon; forming HSG from the undoped silicon of the exposed sidewallsurface; forming a capacitor dielectric layer proximate the storagenode; and forming a complementary capacitor plate proximate thecapacitor dielectric layer.
 14. The method of claim 13 wherein the dopedsilicon comprises polysilicon and the undoped silicon comprisessubstantially amorphous silicon.
 15. The method of claim 13 wherein thestep of forming the silicon material comprises forming a layer of dopedsilicon between two layers of undoped silicon.
 16. The method of claim13 wherein the step of forming the silicon material comprises forming alayer of doped polysilicon between two layers of unidoped substantiallyamorphous silicon.
 17. A method of forming a capacitor comprising thefollowing steps: forming an insulative layer over a node locationdefined by a doped region of the semiconductor substrate; forming anopening through the insulative layer to the node location; forming anundoped silicon layer within the opening to narrow the opening, aportion of the undoped silicon layer physically contacting the nodelocation; forming a doped silicon layer within the narrowed opening andin contact with the undoped silicon layer, the undoped silicon layer anddoped silicon layer together filling the opening and defining acapacitor storage node; forming a capacitor dielectric layer proximatethe storage node; and forming a complementary capacitor plate proximatethe capacitor dielectric layer.
 18. The method of claim 17 wherein theundoped silicon layer comprises substantially amorphous silicon.
 19. Themethod of claim 17 wherein the doped silicon layer comprisespolysilicon.
 20. The method of claim 17 further comprising: removing aportion of the insulative layer to expose a sidewall surface of thestorage node comprising the undoped silicon layer; and forming ruggedpolysilicon from the exposed sidewall surface.
 21. The method of claim17 further comprising: exposing a surface of the capacitor storage nodecomprising undoped silicon; exposing a surface of the capacitor storagenode comprising doped silicon; and substantially selectively forming HSGpolysilicon from the exposed capacitor storage node surface comprisingundoped silicon and not from the exposed capacitor storage node surfacecomprising doped silicon.
 22. The method of claim 21 wherein theformation of the rugged polysilicon comprises: in situ HF cleaning ofthe exposed sidewall surface; seeding the exposed sidewall surface withpolysilicon; and annealing the seeded sidewall surface at about 560° C.for about 20 minutes.
 23. The method of claim 21 wherein the formationof the rugged polysilicon comprises: in situ HF cleaning of the exposedsidewall surface; seeding the exposed sidewall surface with polysilicon;annealing the seeded sidewall surface at about 560° C. for about 20minutes; and a polysilicon etch after the annealing to remove anymonolayers of silicon.
 24. A method of forming a capacitor comprisingthe following steps: forming an insulative layer over a node locationdefined by a doped region of the semiconductor substrate; forming anopening through the insulative layer to the node location; forming afirst undoped silicon layer within the opening to narrow the opening, aportion of the undoped silicon layer physically contacting the nodelocation; forming a doped silicon layer within the narrowed opening tofurther narrow the opening; forming a second undoped silicon layerwithin the further narrowed opening and in contact with the dopedsilicon layer; the first undoped silicon layer, second undoped siliconlayer and doped silicon layer together filling the opening and defininga capacitor storage node; removing a portion of the insulative layer toexpose a sidewall surface of the storage node comprising the firstundoped silicon layer; forming rugged polysilicon on the exposedsidewall surface; forming a dielectric layer proximate the storage node;and forming a cell plate layer proximate the dielectric layer.
 25. Themethod of claim 24 further comprising: exposing a surface of thecapacitor storage node comprising the second undoped silicon layer;exposing a surface of the capacitor storage node comprising the dopedsilicon layer; and substantially selectively forming HSG polysiliconfrom the exposed capacitor storage node surface comprising undopedsilicon and not from the exposed capacitor storage node surfacecomprising doped silicon.
 26. A method of forming a capacitorcomprising: forming an insulative layer over a node location defined bya doped region of the semiconductor substrate; forming an openingthrough the insulative layer to the node location; filling the openingwith silicon material, the silicon material comprising doped silicon andundoped silicon and defining a capacitor storage node, the undopedsilicon being in contact with the node location; removing a portion ofthe insulative layer to expose a sidewall surface of the storage node,the exposed sidewall surface comprising undoped silicon; forming HSGfrom the undoped silicon of the exposed sidewall surface; forming acapacitor dielectric layer proximate the storage node; and forming acomplementary capacitor plate proximate the capacitor dielectric layer.27. The method of claim 26 wherein the doped silicon comprisespolysilicon and the undoped silicon comprises substantially amorphoussilicon.
 28. The method of claim 26 wherein forming the silicon materialcomprises forming a layer of doped silicon inside a layer of undopedsilicon.
 29. The method of claim 26 wherein filling the opening withsilicon material comprises forming a layer of doped polysilicon within alayer of undoped substantially amorphous silicon.
 30. A method offorming a capacitor comprising: forming an insulative layer over a nodelocation; forming an opening through the insulative layer to the nodelocation; forming an undoped silicon layer within the opening to narrowthe opening; filling the narrowed opening with a doped silicon layer,the undoped silicon layer and doped silicon layer together defining acapacitor storage node; forming a capacitor dielectric layer proximatethe storage node; and forming a complementary capacitor plate proximatethe capacitor dielectric layer.
 31. The method of claim 30 furthercomprising: exposing a surface of the capacitor storage node comprisingundoped silicon; exposing a surface of the capacitor storage nodecomprising doped silicon; and substantially selectively forming HSGpolysilicon from the exposed capacitor storage node surface comprisingundoped silicon and not from the exposed capacitor storage node surfacecomprising doped silicon.
 32. The method of claim 31 wherein forming HSGpolysilicon comprises: in situ HF cleaning of exposed doped and undopedsilicon surfaces; seeding the exposed undoped silicon surface withpolysilicon; and annealing the seeded surface at about 560° C. for about20 minutes.
 33. The method of claim 31 wherein forming HSG polysiliconcomprises: in situ HF cleaning of the exposed doped and undoped siliconsurfaces; seeding the exposed undoped silicon surface with polysilicon;annealing the seeded surface at about 560° C. for about 20 minutes; anda polysilicon etch after the annealing to remove any monolayers ofsilicon.
 34. A method of forming a capacitor comprising: forming aninsulative layer over a portion of a semiconductor substrate; forming anopening in the insulative layer to expose a node location on the portionof the semiconductor substrate; forming an undoped silicon layer withinthe opening; filling the opening with doped silicon; removing a portionof the insulative layer to expose a portion of the undoped siliconlayer; selectively converting the exposed portion of the undoped siliconlayer, but not unexposed portions of the undoped silicon layer orexposed or unexposed portions of the doped silicon, to hemisphericalgrain polysilicon; forming a capacitor dielectric layer atop exposedportions of the doped silicon and undoped silicon layer; and forming acomplementary capacitor plate atop the capacitor dielectric layer. 35.The method of claim 34, wherein the capacitor is fabricated as part of amicroprocessor circuit.
 36. The method of claim 34, wherein thecapacitor is integrated into a DRAM cell.
 37. A method of forming acapacitor comprising: forming an insulative layer over a portion of asemiconductor substrate; forming an opening in the insulative layer toexpose a node location on the portion of the semiconductor substrate;forming a silicon pedestal in the opening, the silicon pedestalcomprising a solid core of doped silicon and an outer layer of undopedsilicon; etching the insulative layer to expose a portion of thepedestal; selectively converting exposed portions of the undopedsilicon, but not unexposed portions of the undoped silicon or exposed orunexposed portions of the doped silicon, to hemispherical grainpolysilicon; forming a capacitor dielectric layer atop exposed portionsof the doped silicon and undoped silicon layer; and forming acomplementary capacitor plate atop the capacitor dielectric layer. 38.The method of claim 37, wherein forming a silicon pedestal in theopening comprises: forming a layer of undoped silicon that is in contactwith the node location; and forming the solid core of doped siliconwithin the opening and separated from the node location by the undopedsilicon.
 39. The method of claim 37, wherein forming a silicon pedestalin the opening comprises: forming a layer of undoped silicon in theopening, the undoped silicon being in contact with the node location;and filling the opening by forming the solid core of doped siliconwithin the opening, the doped silicon being separated from the nodelocation by the undoped silicon.